Practice controlling the distance of your putts by putting tees around the hole and taking putts trying to stop them all inside the circle formed by the tees
The grain of a green usually grows towards large bodies of water or the setting sun, use this little trick of scraping the green to learn and understand where and what grain is
Your practice swing is your rehearsal and thinking swing where you do any work you need for that shot, once you get up to the ball all thinking must stop and muscle memory must take over